Key message
Plants with high P-use efficiency adapted more effectively via increased organic acid content in roots and root exudates than those with low P-use efficiency. Plants with high P-use ...efficiency also redistributed P in their tissues as an adaptive response, when organic acid exudation did not improve P-use efficiency.
Increased organic acid exudation enables plants to cope with low-phosphorus (P) stress conditions. We aimed to clarify the variation in organic acid exudation strategies among different breeding genotypes presenting high-phosphorous (P) use efficiency. In this study, Chinese fir
Cunninghamia lanceolata
(Lamb.) Hook. seedlings differing in P-use efficiency were compared regarding low-molecular weight organic acid content in roots and root exudates under low-P stress conditions, and dry weight and P-use efficiency also were examined. Compared to the genotype characterized by low P-use efficiency (M24), passive low-P tolerance (M1) or active capture of soil P (M4) genotypes effectively increased organic acid content in roots and root exudates. Although M1 was more sensitive to low P than M4, the former exhibited a specific tolerance to low P. Accordingly, the production of organic acids was slower, and the resultant stress response was less effective in M1 than in M4. Organic acid exudation did not improve P-use efficiency, given the absence of insoluble P in the rhizosphere, but M1 and M4 redistributed P in the tissues as an adaptive response. M4 also increased the root/shoot ratio and allocated more assimilation to root system to enhance P acquisition under low-P condition. In conclusion, the studied genotypes revealed different organic acid exudation strategies. Plants with high P-use efficiency adapted more effectively than those with low P-use efficiency. Metabolic and energy-use adjustments by plant organs, which facilitate plants’ passive adaptation under P-stress, are important survival strategies that allow adaptation to low-P environments.
Non-structural carbohydrates (NSCs) are labile components in forest litter that can be released quickly at the early stage of litter decomposition and accelerate the metabolic turnover of soil ...microorganisms, which is essential for the formation of forest soil organic matter. Therefore, understanding the NSCs response mechanisms to forest litter at different altitudes is critical for understanding nutrient cycling in the forest soil under climate change conditions. In this study, we used the net bag decomposition method to observe the dynamics of NSCs release in Chinese fir topsoil and canopy litter at four altitudes for 360 days based on the climatic zone characteristics distributed vertically along the elevation of Wuyi Mountain. The release of NSCs in Chinese fir litter rise gradually with height increases during the decomposition. The difference of the cumulative release percentage of soluble sugar between different altitudes is more significant than that of starch. The response of the NSC content in different treatment groups at four altitudes are different. The release of NSCs in the leaf canopy litter is higher than that in the leaf topsoil litter. On the contrary, the release of NSCs in the mixture of leaf and twig topsoil litter is higher than that in the mixture of leaf and twig canopy litter. Taken together, this study is of great significance for a comprehensive understanding of the effect of climate change on NSCs during the decomposition of Chinese fir litter.
Chinese fir (Cunninghamia lanceolata (Lamb) Hook) is a commercially valuable timber species that is widely planted in southern China and accounts for 6.1% of the global plantation forests. However, ...appropriate planting density that ensures high plantation productivity is largely unexplored in this species. The aim of the study was to examine tree growth, biomass production, and its allocation among different organs in relation to initial planting density, and to examine whether planting density has an impact on root development. Mortality, diameter at breast height and tree-height of all trees were determined and measured in wider (2.36 × 2.36 m), intermediate (1.83 × 1.83 m) and narrow (1.44 × 1.44 m) spacing with stand density of 1450 trees ha−1, 2460 trees ha−1 and 3950 trees ha−1, respectively. In each stand, three plots of 20 × 20 m at a distance of 500 m were delineated as the sampling unit. Biomass was determined by destructive sampling of trees in each stand and developing allometric equations. Root morphological traits and their spatial distribution were also determined by carefully excavating the root systems. The results showed an increase in diameter of trees with decreasing stand density while tree height was independent of stand density. Biomass production of individual trees was significantly (p < 0.05) less in high-density stand (32.35 ± 2.98 kg tree−1) compared to low-density stand (44.72 ± 4.96 kg tree−1) and intermediate-density stand (61.35 ± 4.78 kg tree−1) while stand biomass production differed significantly in the order of intermediate (67.63 ± 5.14 t ha−1) > high (57.08 ± 3.13 t ha−1) > low (27.39 ± 3.42 t ha−1) stand density. Both average root length and root volume were significantly (p < 0.05) lower in the high-density stand than stands with low and intermediate density. Analysis of spatial distribution of root systems revealed no overlap between roots of neighboring trees in the competition zone in low-density stand, a subtle overlap in the intermediate density stand and larger overlap in the high-density stand. It can be concluded that better growth and biomass production in intermediate density stand could be explained by better root structural development coupled with minimal competition with understory vegetation and between trees; thus intermediate stand density can be optimal for sustaining long-term productivity and may reduce the management cost in the early phase of the plantation.
Background and Objectives: Fungi degrade lignin and other fibers, thus playing an essential role in the decomposition of Phyllostachys edulis (Carrière) J.Houz. (Moso bamboo) stumps. Herein, we ...characterized key soil fungal communities near different levels of decomposing Moso bamboo stumps (mildly, moderately, and heavily decayed). Materials and Methods: High-throughput sequencing technology was used to analyze the soil fungal communities inside and outside of mild, moderate, and heavy decomposing Moso bamboo stumps. Results: We found nine phyla, 30 classes, 77 orders, 149 families, and 247 genera of soil fungi near the bamboo stumps. Soil fungi OTUs and diversity and richness indices were lower outside than inside the stumps, and decreased with increasing degrees of decay. Inside the bamboo stumps, Soil fungi OTUs and diversity and richness indices were the highest and lowest in moderate and heavy decay bamboo stumps, respectively. Ascomycota dominated inside (from 81% to 46%) and outside (from 69% to 49%) the stumps, and their relative abundance gradually decreased with decomposition, whereas that of Basidiomycota increased outside the stumps (from 17% to 49%). Two-way ANOVA showed that the interaction between the two factors of occurring inside and outside the bamboo stumps and the degree of decay, significantly affected Chytridiomycota and Penicillium (p < 0.001) and significantly affected Mucoromycota (p < 0.05). The abundance of different genera was significantly correlated with saprotrophic functional groups. Conclusion: Changes in the structure and functional groups of soil fungal communities may play an important role during different levels of decomposition of Moso bamboo stumps. This study provides a scientific basis for screening functional fungal strains that promote the decomposition of Moso bamboo stumps.
The root is the main organ of a plant for absorbing resources and whose spatial distribution characteristics play an important role in the survival of seedlings after afforestation. Chinese fir ...(Cunninghamia lanceolata) is one of China’s most important plantation species. To clarify the effects of propagation methods on root growth and spatial distribution characteristics of Chinese fir trees, sampled trees cultivated by seed germination, tissue culture, and asexual cutting of Chinese fir were taken as the research objects. The root morphology, geometric configuration, and spatial distribution characteristics of different trees were analyzed. The influence of geometric root morphology on its spatial distribution pattern was explored by correlation analysis, and the resource acquisition characteristics reflected by the roots of Chinese fir trees with different propagation methods are discussed. The main results showed that the root mean diameter (1.56 mm, 0.95 mm, and 0.97 mm), root volume (2.98 m3, 10.25 m3, and 4.07 m3), root tip count (397, 522, and 440), main root branch angle (61°, 50° and 32°) and other geometric configurations of Chinese fir under seed germination, tissue culture and rooted cutting respectively, were significantly different, which resulted in different distribution characteristics of roots in space. Chinese fir seed germination had noticeable axial roots, and the growth advantage was obvious in the vertical direction. A fishtail branch structure (TI = 0.87) was constructed. The shallow root distribution of tissue culture and rooted cutting was obvious, and belonged to the fork branch structure (TI = 0.71 and 0.74, respectively). There was a tradeoff in the spatial growth of the root system of Chinese fir trees with different propagation methods to absorb nutrients from heterogeneous soil patches. A negative correlation was present between the root system and root amplitude. There was an opposite spatial growth trend of Chinese fir trees with different propagation methods in the vertical or horizontal direction. In conclusion, selecting suitable propagation methods to cultivate Chinese fir trees is beneficial to root development and the “ideal” configuration formation of resource acquisition to improve the survival rate of Chinese fir afforestation.
Studying the effects of different concentrations of ethephon on morphological and physiological changes in the roots of Chinese fir (Cunninghamia lanceolata Lamb. Hook.) seedlings under P deficiency ...can reveal the internal adaptive mechanisms of these plants under nutrient stress. Herein, we investigated the effects of different ethephon and cobalt chloride concentrations under normal P supply and P deficiency. A significant effect (p < 0.05) of exogenous additive application was observed on the development of Chinese fir root length, surface area, and volume. These root development indices showed maximum values when the ethephon concentration was 0.01 g kg−1 under normal P supply and P deficiency, and they were significantly different from those under 0.04 g kg−1 ethephon treatment. Similarly, the indices showed maximum values when CoCl2 concentration was 0.01 g kg−1 under P deficiency and was significantly different (p < 0.01) from those under 0.2 g kg−1 CoCl2 treatment. Under normal P supply, an increase in ethephon concentration caused superoxide dismutase (SOD; E.C. 1.15.1.1) activity to decrease and peroxidase (POD; E.C. 1.11.1.X) activity to increase gradually. Conversely, CoCl2 addition (0.01 g kg−1) promoted SOD and POD activities under P deficiency. There were no significant differences (p > 0.05) in malondialdehyde content of seedlings among ethephon or CoCl2 treatments. In conclusion, ethylene plays a significant role in adaptative mechanisms underlying stress resistance in plants, prompting them to respond to P starvation and improving seedlings’ tolerance to P-deficient conditions.
This paper assesses the interrelationship between poverty, climatic and non-climatic shocks, and shock coping strategies adopted by farm-based rural households in Nepal. An analysis is based on a ...comprehensive data set collected from 300 randomly selected households from three purposively chosen villages of Gandaki province. The study utilizes binary and ordered probit regression models to analyze the determinants of poverty, shocks, and coping strategies. Findings reveal that the Dalit (ethnic group), large-sized, and agricultural households are more likely to be characterized as poor. The study further shows that majority of the households are exposed to the severe shock of climatic types. Patterns of shock exposure vary with the household’s characteristics. In particular, poor households in the hills primarily dependent on forest for livelihood are more likely to experience severe shocks. Further analyses indicate that the households ex-post choose dissaving, borrowing, shifting occupation, and migration to cope with severe climatic shocks. The analyses also reveal that the nature of shocks, socio-economic, demographic, geographic contexts, and factor endowments effect adopting a particular coping strategy. Findings suggest household level-specific support should be provided to mitigate the effects of shock, and appropriate measures are taken to protect their means of living.
The calorific value and construction cost of leaves reflect the utilization strategy of plants for environmental resources. Their genetic characteristics and leaf functional traits as well as climate ...change affect the calorific values. This study explores the differences in energy investment strategies and the response characteristics of energy utilization in leaves to climate change among nine clones of Chinese fir (
). Considering the objectives, the differences in the energy utilization strategies were analyzed by determining the leaf nutrients, specific leaf area, and leaf calorific value and by calculating the construction cost. The results showed a significant difference in the ash-free calorific value and construction cost of leaves among different Chinese fir clones (
< 0.05). There were also significant differences in leaf carbon (C) content, leaf nitrogen (N) content, specific leaf area, and ash content. The correlation analysis showed that leaves' ash-free calorific value and construction cost were positively correlated with the C content. Principal component analysis (PCA) showed that P2 is inclined to the "fast investment return" energy investment strategy, while L27 is inclined to the "slow investment return" energy investment strategy. Redundancy analysis (RDA) indicates that the monthly average temperature strongly correlates positively with leaf construction cost, N content, and specific leaf area. The monthly average precipitation positively impacts the ash-free calorific value and construction cost of leaves. In conclusion, there are obvious differences in energy investment strategies among different Chinese fir clones. When temperature and precipitation change, Chinese fir leaves can adjust their energy investment to adapt to environmental changes. In the future, attention should be paid to the impact of climate change-related aspects on the growth and development of Chinese fir plantations.
The diversity of the rhizosphere arbuscular mycorrhizal fungi (AMF) community is a crucial factor affecting root-soil interaction. They can absorb carbohydrates from the host body and return the ...nutrient elements from the soil to the host. Using 15 Chinese fir (
Cunninghamia lanceolata
Lamb. Hook.) clones, the AMF richness, abundance and community structure in “Root system-Rhizosphere soil-Bulk soil” were obtained by Real-time quantitative PCR (qPCR) and Illumina Miseq sequencing techniques. The results showed that under the same Chinese fir clone, the total amount of AMF was in the order of rhizosphere soil > root system > bulk soil. The species diversity and uniqueness of AMF were in the order of root system > rhizosphere soil > bulk soil. There was a significant correlation between soil-available phosphorus and AMF diversity and its dominant genera and species. Regarding AMF abundance, Chinese fir clone S18 is the highest, followed by clones Y061 and P17. There was a significant difference in AMF richness among different clones, and
Glomus
was the dominant genus of AMF. The AMF species diversity of P17 and S2 in roots and rhizosphere soil was high, indicating a good symbiosis between roots and the AMF community. However, the AMF diversity of clones P11 and P41 was low, and the variation of AMF community composition in the group was small. The root-soil interaction caused the AMF community to gather in the rhizosphere but had less symbiosis present with roots. Still, the AMF diversity of the rhizosphere soil of both clones was high. There was a significant correlation between the soil-available phosphorus content and the species diversity of AMF and its dominant genera and species. In conclusion, Clone P17 has high AMF richness and abundance and forms a good symbiosis with AMF, which could be a nutrient-efficient clone of Chinese fir.
Effects of light quality on phenotypic plasticity in Cunninghamialanceolata (Lamb.) Hook. seedlings during growth and development, and the underlying mechanisms, were investigated. The seedlings ...showed distinct morphological adjustments when exposed to an equal photosynthetic photon flux density (400 μmol·m−2·s−1) of different light qualities: monochromatic blue (BL), monochromatic red (RL), monochromatic far-red (FrL), mixed RL and FrL at 1:1 (RFr1:1L), mixed RL and FrL at 1:2 (RFr1:2L), and multi-wavelength white (WL, control). Compared with WL, FrL and BL significantly promoted height increment. However, BL was unfavorable for root growth. The seedling biomass was lower and the root-to-shoot ratio was smaller under BL. RL promoted leaf area enlargement, root growth, axillary bud number, and increased the root-to-shoot ratio, but inhibited stem elongation. Low R/Fr ratios or increased FrL proportion increased seedling stem elongation. The seedling growth under RFr1:1L treatment was poorer than that under other treatments; however, the number of axillary buds was the highest. The plasticity of leaf morphology traits was lower in different treatments, and that of axillary bud traits was crucial in the adaptation of C. lanceolata to light quality. Precise management of light quality and wavelength in controlled environments may maximize the economic efficiency of forest production and enhance its quality.
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